The industrial, scientific and medical (ISM) radio bands are portions of the radio spectrum reserved internationally for industrial, scientific, and medical applications other than telecommunications. Examples include radio frequency process heating, microwave ovens, and medical diathermy machines. Due to interference concerns, these devices were limited to certain frequency bands. Despite original intentions, the fastest growing uses of these bands are now short-range, low-power wireless communication systems like Bluetooth, Wi-Fi, and baby monitors, which can operate without a license. The ISM bands are also still used for their intended industrial, scientific, and medical purposes.